1. Field of the Invention
The present invention relates to vibrators, and, more particularly, to vibrators utilizing eccentric weights to produce the desired vibrations.
2. Description of the Prior Art
Vibrators are used to induce vibrations in various types of industrial equipment for diverse purposes such as feeding material, screening material, or dislodging material. In some applications, such as in a two mass vibrating system used to feed material at a predetermined rate, the magnitude of the stroke of the vibrator is important.
One method of producing vibrations in a vibrator is by use of a rotating shaft with an eccentric weight, or weights thereon. Frequently, as shown, for example, in the U.S. Pat. Nos. 2,934,202; 3,396,294; 3,920,222; and 3,922,043 two or more eccentric weights are used which can be set at different angular positions on the driven shaft relative to each other to change the total effective eccentricity of the weights, and therefore to change the stroke of the vibrator. In the usual eccentric weight vibrator, it is difficult to change the relative angularity of the weights, and the vibrator must be stopped to accomplish the modification.
In at least the following patents (U.S. Pat. Nos. 3,920,222; 698,103; 2,677,967; 3,091,712; 3,192,839; and Russian Pat. No. 274430), apparatus has been provided for the purpose of changing the angle between the eccentric weights while the vibrator is running.